Nuclear forensics is an important tool in the fight against illicit trafficking of nuclear and other radioactive material and assists authorities if a law has been broken. Such materials are commonplace in energy, medicine, industry and research, but if they go out of regulatory control, a State must be ready to respond. The IAEA Division of Nuclear Security, together with the US National Nuclear Security Administration (NNSA), recently conducted an International Nuclear Forensics Methodologies training course at Pacific Northwest National Laboratory (PNNL) for 26 experts from 10 Member States to learn about the specialized nature of nuclear forensics.